Permitted or not, this is really a bad idea to create so many different image sizes. You are creating 12 custom image sizes, WordPress will create 3 default sizes + 1 original image. So you will be creating 16 image copies for a single image, which is A LOT, as it will be using lots of server reources.
Also note, many users might not even use the features. For example if someone is using 3 columns masonry layout, s/he wont be using 4 columns layout as well. Similarly with the portfolio, blog grid, team image sizes. You are generating too many extra image sizes which will never be used by a user.
Any wordpress developer can do that if you pay reasonable money (a few thousands $) for that. Why won’t you just buy a similar theme if that specific one is not available for sale?
Any themeforest author / community member attendning WordCamp Europe 2014?